import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner num = new Scanner(System.in);
        int n =num.nextInt();
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            sum = i*n;
            sum += sum;
        }
        System.out.println(sum);
    }
}
